# GPT-5 vs GPT-6 Luna

GPT-6 Luna is one of OpenAI's newest models and GPT-5 an earlier one, so this is also what moving up costs or saves. GPT-6 Luna is the cheaper of the 2: for the same tokens, 3 read for each 1 written, GPT-5 costs 17 times as much. Below are both price lists, what 8 everyday jobs cost a month on each, and how many tokens the same text takes on each, which can change the answer.

- Page, with a calculator for your own job: https://tecyfy.com/prices/compare/gpt-5-vs-gpt-6-luna
- Makers: GPT-5 from OpenAI, GPT-6 Luna from OpenAI

## Price per million tokens, in US dollars

| | GPT-5 | GPT-6 Luna |
| --- | --: | --: |
| Input | $1.25 | $0.10 |
| Cached input | $0.125 | $0.01 |
| Cache write | not listed | $0.125 |
| Output | $10 | $0.50 |
| Blend, 3 read for each 1 written | $3.4375 | $0.20 |
| Batch input | $0.625 | $0.05 |
| Batch output | $5 | $0.25 |
| Long prompt input (above 272K on GPT-6 Luna) | $1.25 | $0.20 |
| Long prompt output | $10 | $0.75 |
| Context window, tokens | 400K | 1.05M |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 150 | 156 |
| Longest answer, tokens | 128K | 128K |

## What 8 everyday jobs cost a month on each

Each job at its usual runs a day, for 30 days, at the standard price.

| Job | Tokens in, out, runs a day | GPT-5 | GPT-6 Luna |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $16.13 | 84 cents |
| A hard question, with thinking | 300, 1,400, 100 | $43.13 | $2.19 |
| A long report, summarised | 60,000, 2,000, 20 | $57.00 | $4.20 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $320 | $21.96 |
| A support bot's reply | 4,000, 300, 2,000 | $345 | $22.20 |
| Sort a message into a category | 250, 5, 50,000 | $544 | $41.25 |
| Read an invoice into fields | 1,500, 250, 1,000 | $131 | $8.25 |
| Review a pull request | 25,000, 4,500, 50 | $114 | $7.13 |

## Questions

### Which is cheaper, GPT-5 or GPT-6 Luna?

GPT-6 Luna is cheaper: $0.10 per million tokens read and $0.50 per million written, against $1.25 and $10 on GPT-5. On a mix of 3 tokens read for each 1 written, GPT-5 costs 17 times as much.

### Which is better, GPT-5 or GPT-6 Luna?

On the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks, GPT-6 Luna scores 156 and GPT-5 150, above the top of the range of doubt around GPT-5's score (GPT-5 is 150). One score is an average; test both on your own work before you switch.

### What does a support bot cost a month on GPT-5 and GPT-6 Luna?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, it costs $345 a month on GPT-5 and $22.20 on GPT-6 Luna: GPT-5 costs 16 times as much for this job.

### What does an AI agent task cost on GPT-5 and GPT-6 Luna?

One 40-turn task that reads 2,800,000 tokens in all, 90 percent of them from cache, and writes 40,000, costs $1.07 on GPT-5 and 7.3 cents on GPT-6 Luna. At 10 tasks a day that is $320 and $21.96 a month.

### Which has the larger context window, GPT-5 or GPT-6 Luna?

GPT-6 Luna, with 1.05M tokens against 400K on GPT-5. The window holds your instructions, the files you attach, the conversation so far and the answer, all at once.

### Does the same text take the same number of tokens on GPT-5 and GPT-6 Luna?

Yes, both are counted the same way: our lesson "How AI writes", 1,700 words long, is about 2,100 tokens on each.

### Is it cheaper to move from GPT-5 to GPT-6 Luna?

Yes, per token: GPT-6 Luna costs $0.10 per million tokens read and $0.50 written, against $1.25 and $10 on GPT-5, which costs 17 times as much for the same tokens. Run your own tasks on it before you switch, since answers, length and thinking can differ.

### Can I pay less on GPT-5 and GPT-6 Luna for work that can wait?

Yes, on both. With a batch, where you collect the answers later instead of at once, GPT-5 costs $0.625 per million tokens read and $5 written, and GPT-6 Luna $0.05 and $0.25.

## Sources

- [OpenAI: API prices](https://developers.openai.com/api/docs/pricing)
- [Epoch Capabilities Index, by Epoch AI (CC BY 4.0)](https://epoch.ai/benchmarks/eci)

## Other comparisons

- [GPT-6 Luna vs GPT-6 Sol](https://tecyfy.com/prices/compare/gpt-6-luna-vs-gpt-6-sol.md)
- [GPT-5.6 Sol vs GPT-6 Luna](https://tecyfy.com/prices/compare/gpt-5-6-sol-vs-gpt-6-luna.md)
- [GPT-5.6 Terra vs GPT-6 Luna](https://tecyfy.com/prices/compare/gpt-5-6-terra-vs-gpt-6-luna.md)
- [GPT-5.6 Luna vs GPT-6 Luna](https://tecyfy.com/prices/compare/gpt-5-6-luna-vs-gpt-6-luna.md)
- [GPT-5.5 vs GPT-6 Luna](https://tecyfy.com/prices/compare/gpt-5-5-vs-gpt-6-luna.md)
- [GPT-5.5 pro vs GPT-6 Luna](https://tecyfy.com/prices/compare/gpt-5-5-pro-vs-gpt-6-luna.md)